Factor G, a newly discovered, vitamin-like dietary agent, is necessary for optimal growth, nitrogen balance, and effective food utilization of animals in purified amino acid diets. Factor G increases the efficiency of food utilization by 30 to 40 per cent. The agent is found in liver, yeast, and other sources. Two forms of the factor, G1 and G2, can be distinguished chemically. Objectives of the project are to isolate and identify factor G1 and G2, obtain them in synthetic form, and study their mode of action, emphasizing relationship to the utilization of protein, fat and carbohydrate. Long term factor G deficiencies shall be studied, the significance of factor G for mice, guinea pigs, chicks, and other species shall be investigated, and its effects on protein synthesis, amino acid utilization, and other aspects of intermediary metabolism shall be analyzed.